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How to set environment variables for a systemd service in?
The MySQL manual states the service setup is done simply as (example only): This is the preferred method which is to create and/or edit an override file that contains the environment variables. The command to create/edit the override file is:
Where to find the environment file in systemd?
For example: The environment file can be any, as defined by the EnvironmentFile attribute in the service, however, it could be specific to the version and distribution of Linux. Some older versions will expect it to be in /etc/sysconf (for Redhat-based distributions) versus /etc/default (for Debian-based distributions).
Why is the environment variable kept in a unit file?
The advantage of that is that the variable is kept in a single file with the unit. Therefore, the unit file is easier to move between systems. However, the above solution doesn’t work well when sysadmin is supposed to change the value of the environment variable locally.
Is the environment variable supposed to be constant?
The answer depends on whether the variable is supposed to be constant (that is, not supposed to be modified by user getting the unit) or variable (supposed to be set by the user). Since it’s your local unit, the boundary is quite blurry and either way would work.
How to use systemd for basic value assignment?
In basic value assignment, it seems similar, but it is not the same thing. Prefered solution for this by Gentoo is to put everything into service file and configuration file of the service and not to use additional conf.d file. Use this only as fast hack to run OpenRC service as systemd one.
How to override the setting of an environment variable?
Their format is simply KEY=VALUE, with possible empty lines and comments in between. Settings from these files override settings made with Environment=. If the same variable is set twice from these files, the files will be read in the order they are specified and the later setting will override the earlier setting.